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Cytokeratin 13 (CK13) is a type I acidic low molecular weight cytokeratin, which is mainly expressed in urothelium and in the squamous epithelium of various sites of origin. Loss of CK13 has been implicated in the development and progression of squamous epithelial neoplasms. To comprehensively determine CK13 expression in normal and neoplastic tissues, a tissue microarray containing 10,439 samples from 131 different tumor types and subtypes as well as 608 samples of 76 different normal tissue types was analyzed by immunohistochemistry. CK13 immunostaining was detectable in 42 (32.1%) of the 131 tumor categories including 24 (18.3%) tumor types with at least one strongly positive case. The highest rate of positive staining was found in various urothelial neoplasms (52.1-92.3%) including Brenner tumor of the ovary (86.8%) and in squamous cell carcinomas from various sites of origin (39.1-77.6%), Warthin tumors of parotid glands (66.7%), adenosquamous carcinomas of the cervix (33.3%), thymomas (16.0%), and endometroid carcinomas of the ovary (15.3%). Twenty other epithelial or germ cell neoplasms showed - a usually weak - CK13 positivity in less than 15% of the cases. In bladder cancer, reduced CK13 expression was linked to high grade and advanced stage (p 0.0001 each). In squamous cell carcinoma of the cervix, reduced CK13 immunostaining was related to high grade (p = 0.0295) and shortened recurrence-free (p = 0.0094) and overall survival (p = 0.0274). In a combined analysis of 1,151 squamous cell carcinomas from 11 different sites of origin, reduced CK13 staining was linked to high grade (p = 0.0050). Our data provide a comprehensive overview on CK13 expression in normal and neoplastic human tissues. CK13 expression predominates in urothelial neoplasms and in squamous cell carcinomas of different organs, and a loss of CK13 expression is associated with aggressive disease in these tumors.

Polymorphisms of the base excision repair gene APE1 may be associated with an increased risk for developing prostate cancer. In other cancer types, altered APE1 protein expression is a candidate prognostic marker. Using immunohistochemistry, we thus analyzed APE1 expression in 9763 prostate cancers in a tissue microarray (TMA) with attached clinical and molecular data. The comparison with normal prostate tissue revealed an upregulation of APE1 in cancer samples. APE1 immunostaining was considered weak in 20.2%, moderate in 36.7%, and strong in 33.4% of cancers. Strong APE1 expression was markedly more frequent in prostate cancers harboring the TMPRSS2:ERG fusion (52.9%) than in ERG-negative cancers (19.1%, P

High doses of ultraviolet radiation (UVR) have well-known inhibitory effects upon dermatophytes. In the present study, the effect of repetitive low doses of UVR on mycelial growth of dermatophytes was tested. Pellets of Trichophyton rubrum, T. mentagrophytes and Microsporum canis were placed between two thin layers of Sabouraud glucose agar. Obverse, reverse or both sides of these 'sandwich' agars were irradiated for 10 days twice daily with 0.13 or 0.17 J cm-2 UVB. To simulate microaerophilic conditions, one or both agar sides were covered by transparent airtight plastic lids. In addition, T. rubrum was also grown as usual on plates of Sabouraud glucose agar without any covering, and irradiated on its obverse side twice daily with UVA (13.5 J cm-2), UVB (0.17, 0.34 or 0.69 J cm-2) or infrared light, or once only with 3.8-15.1 J cm-2 UVB. As a result, thallus diameters of all strains were found to be reduced by repetitive UVB irradiation under both aerobic and microaerophilic growth conditions. T. rubrum was unaffected by infrared irradiation, responded with an increased pigmentation to UVA (13.5 J cm-2 twice daily) and was inhibited by a single dose of 15.1 J cm-2 UVB. Negative phototropism of dermatophytes is a new observation. It may be biologically relevant as a mechanism to evade harmful doses of UVR.